This area contains links to posts within the forum area on various topics. It's designed to help you find the answers to the most common questions about AJS and Matchless machines.Only club members can create entries witin this area.

The question of how long is reasonable to wait for the oil to start returning in the oil tank when rebuilding a heavyweight single seems to come up a lot. As I was trying to seal some major leaks from both pump plates on my 55 G80 engine I thought I would time things.So I drained the oil tank, then cleaned the oil tank filter during which operation probably half the oil in the filter housing was removed/spilt. I then drained the sump followed by replacing both pump plate gaskets. Despite emptying the oil, both ends of the pump leaked copious amounts of oil whilst the gaskets were replaced. So in all pretty much like a newly rebuilt engine in terms of little oil in it, except I knew there was still plenty of oil around so did not do what I usually would with a newly built engine (prime the oil by pouring about 4 fl oz down each pushrod tube to make sure the bottom was oiled and which would of course filter through and prime the sump).But without any oil added how long did it take? Well after 7 minutes of running the engine on a fast tickover even I was beginning to worry though I was sure all was well. The oil level in the tank was clearly dropping but only slowly so not that obvious. Finally after about 8 and a half minutes the oil began to pulse out of the return. The level in the oil tank had probably dropped by 1/3 as the sump filled, the return pocket housing the filter filled, and the oil pipes to the rockerbox refilled.

I did say it was nail biting stuff! Thanks for taking the time (no pun intended) to time how long it takes for oil to return Clive. When I rebuilt the LCS I followed Itma's advice and filled the filter let it drain down to the sump and filled again. Poured down the push rod tubes and left the cover off and it still took what felt like an eternity for the oil to not only get to the top but also return to the tank.

What is NOT conducive to a fast recommencement of scavenge oil is that if the breather system is working very efficiently, as it should be, the crankcases are under a negative gas pressure (slight vacuum) This in effect increases the head or height of the oil lift required. If one was to block the breather pipe before starting, this will prevent gas evacuation and additionally will allow pressurisation of the crankcase space due to piston blow by...this will help prime the pump....Once the scavenge pump is primed it should work effectively unless there are problems with its efficiency as mentioned on a very recent other question here...ATB...Les

My 1955 G3LS is about the same as Clive's 55 bike, the oil returns more like a waterfall. My 1936 AJS 250 starts to return in less than half that time, the oil pumping straight out, much stronger at least 15 m.m. before falling.Could be the 1936 AJS return faster and pumps stronger as it has exposed valve springs. There being no supply to the top end of the engine. 1937/38 with semi enclosed springs, has oil supply to the top end. This feeds into the back of the enclosed tappet box and is regulated. Oil return is still stronger than the 55 G3LS

This scenario also bothered me with my G80CS. I had never started it since importing from the US. Once I went through the timing and carburetor I did kickstart the bike but got jittery when no oil was returning to the tank.The primary case was off, so I got a big, reversible electric drill, the correct socket for the crankshaft nut and various adaptors to connect it all together.I removed the spark plug, loosened the rocker feed connecting nut and wound the engine over with the drill. Eventually I got oil to the rockers so was then confident that at least the oil pump was pumping, put it back together and started the engine. Its a simple way to ensure you dont damage the engine, they probably are expensive to rebuild.